BEIJING -- China said Friday it would be "difficult" for it to take part in a planned conference on the war in Ukraine next month if Russia did not attend.

While China says it is a neutral party in the Ukraine conflict, it has been criticised for refusing to condemn Moscow for its offensive.

Ukraine is trying to whip up attendance at the June peace conference in Switzerland, where it hopes to win broad international backing for its vision of the terms needed to end Russia's war.

President Volodymyr Zelensky has urged China to take part but Beijing insisted on Friday that any summit would need the participation of Russia, which Ukraine has rejected.

Beijing believes the conference "should have the recognition of Russia and Ukraine, equal participation of all parties and fair discussion of all peace plans," foreign ministry spokeswoman Mao Ning told a regular news conference.

"Otherwise, it is difficult for the conference to play a substantive role in restoring peace," she said.

"The arrangement of the meeting still falls short of China's requirements and the expectations of the international community, making it difficult for China to attend," Mao said.

Moscow has dismissed the idea of a peace summit without Russia as "absurd."

"From the beginning, China has spoken about the futility of holding such summits without Russia's participation," Kremlin spokesman Dmitry Peskov told reporters on Friday.

"Seeking options for a solution to the Ukrainian conflict without Russia's participation is absolutely illogical, futile and a waste of time."

On the sidelines of the Shangri-La Dialogue in Singapore Friday, China's top defence official reiterated Beijing's "objective, impartial position" on the war, according to a spokesman.

"We have honoured our commitment not to provide weapons to either side of the conflict," spokesman Wu Qian said, following the rare meeting between US Defense Secretary Lloyd Austin and China's Dong Jun.

"We have implemented strict controls on exports of military items," Wu said.

"China will continue resolutely to promote peace talks and play a constructive role, but we firmly oppose the United States shifting blame onto us," he said. (AFP)